A second Inner Austrian cadet branch of the Habsburgs ruled over Styria from 1564. Under Archduke Charles II of Inner Austria, Graz became a centre of the Counter-Reformation, expedited by the Jesuits at the University of Graz established in 1585 and continued under Charles' son Archduke Ferdinand II of Habsburg, who became sole rule of all Habsburg hereditary lands and Holy Roman Emperor in 1619. The Protestant population was expelled, including the astronomer Johannes Kepler in 1600. Meanwhile at the time of the Ottoman invasions in the 16th and 17th centuries after the 1526 Battle of Mohács, the land suffered severely and was depopulated. The Turks made incursions into Styria nearly twenty times; churches, monasteries, cities, and villages were destroyed and plundered, while the population was either killed or carried away into slavery.